Abnormalities and genetic disorders can be caused by hereditary factors including autosomal inheritance, X-linked inheritance, and defective chromosomes. They can also be produced by harmful genes or an uneven number of chromosomes. Gene mutations can be inherited from parents or acquired, and hereditary mutations exist in virtually all body cells and can be passed down between generations. Some examples of genetic disorders discussed include sickle cell anemia, hemophilia, Huntington's disease, phenylketonuria (PKU), Tay-Sachs disease, and diabetes.